Films for electrochemical structural elements and method for producing such films

ABSTRACT

The invention relates to a paste-like mass that can be used in electrochemical structural elements, including a heterogeneous mixture of (1.) a matrix (A) containing at least one organic polymer, precursors thereof, or prepolymers thereof, or consisting of said components, (2.) an electrochemically activatable inorganic material in the form of a solid substance (B), said material not being soluble in said matrix and in water, and (3.) a material (C) which is capable of improving the transport of a liquid electrolyte into and the storage thereof within the structural element, with the proviso that said material (C) is not a material which simultaneously has conductivity improving properties, if said solid substance (B) is a material that is suitable as an electrode material. From said mass, layers (films) and electrochemical composite layers can be produced that are subsequently impregnated with an electrolyte solution preferably of electrolytes dissolved in plasticizers for said matrix (A). In this manner, electrochemically active structural elements such as batteries and accumulators are obtained.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 10/148,283,filed Aug. 5, 2002, now U.S. Pat. No. 7,335,321.

FIELD OF THE INVENTION

The present invention relates to novel materials with electrochemicalproperties, in particular to films and to composite layers producedtherefrom as well as to paste-like masses which are suitable for theproduction of said films. The invention is primarily suitable for theproduction of batteries and accumulators, and in particular also forrechargeable systems made in film technology which in the following aredesignated as cells or generally as “systems”, or as electrochemicallyactive or electrochemically activatable composite layers.

BACKGROUND OF THE INVENTION

Since the beginning of the 1970's there have been attempts to produceelectrochemical structural elements such as accumulators or the like inthe form of thin layers. The goal has been to obtain composite filmsthat are both flexible enough that they can be, for instance, rolled upor made to conform to another desired shape and that also haveparticularly favorable charging and discharging properties due to anextremely high contact area between the individual electrochemicalcomponents, such as electrodes and electrolytes, relative to the volumeof the active electrochemical material used. Apart from a fewexceptions, this construction (film technology) was to presentsubstantial advantages. In general, it will not be used only if (a)extreme requirements are to be made on the system, or (b) particularelectrochemical advantages exist.

In patent literature, a number of methods for producing such films hasbeen described. As far as films are concerned that are provided aselectrolyte layers in structural elements to be produced therefrom, twodifferent approaches exist.

According to the first approach, a paste is produced from all essentialcomponents. Said paste then serves as a basic material for the film. Forproducing the paste, a solid electrolyte is dissolved in the pastematerial; thereupon, a wetting or a cross-linking thin layer of saidelectrolyte is deposited within the film by extraction of the solvent.In the U.S. Pat. No. 5,009,970, polyethylene oxide (PEO) is used as apolymer which is mixed with an adequate lithium salt in water, whereby acomplex of the two components is obtained. The PEO is cross-linked byradiation. A hydrogel is obtained that is to be dried subsequently undervacuum. U.S. Pat. No. 5,041,346 also describes an oxymethylenecross-linked variant of an ethylene oxide polymer electrolyte whichadditionally contains a softener. However, it has been reported thatalthough the ion conductivity of such complexes compared to pure solidlithium salt is drastically increased, it is still not sufficient foruse as an electrolyte layer in electrochemical structural elements. Infact, the most homogeneous deposition is obtained by said method;however, the high price of a mechanical instability of the film obtained(tearing, rolling up, sticking) has to be paid. A further disadvantageis that the soluble lithium conductors that are used according to thistechnology are hygroscopic, partly even susceptible to hydrolysis.Moreover, water is not only adsorbed, but usually incorporated ascrystal water. Besides a very complicated storage of the films producedin this manner (storage has to be made in drying chambers), the filmscan practically not be laminated without steam bubbles, since the water,due to the tight bond to said substances, is not extractable byconventional methods. Decontactings, holes to the point of smallexplosion craters and a deliquescence of the laminate are usual results,for which reason said method is advantageously only applicable to pastesonly.

According to the second strategy, a microporous sponge structure isprovided. In this respect, U.S. Pat. No. 5,456,000 describesrechargeable battery cells which are produced from self-supporting filmsby lamination of electrode and electrolyte cells. A film or a membraneis used as positive electrode which has separately been produced fromLiMn₂O₄ powder in a matrix solution of a copolymer and has subsequentlybeen dried. The negative electrode consists of a dried coating of apowderized carbon dispersion in a matrix solution of a copolymer.Between the electrode layers, an electrolyte/separator membrane isprovided. For this purpose, a poly(vinylidene fluoride)hexafluoropropylene copolymer in acetone or THF or the like is reactedwith a plasticizer that is suitable as a solvent for electrolyte salts.The films produced from these components are laminated. For activatingthe battery, it is immersed into the respective electrolyte solution,thereby soaking with the electrolyte solution.

Due to the high proportion of plasticizer, the films show a very badaging resistance; after storage periods of several weeks, modificationsin consistency and brittleness to the point of decomposition to powderare observed which is possibly due to an interaction with environmentalmoisture. Moreover, due to the high proportion of plasticizer,lamination can only be effected at a temperature which is considerablydecreased relative to the melting point of the polymer. Therefore in thevariant described as preferred, the plasticizer is expelled in advance,which requires expensive washing steps. Moreover, the absorptioncapacity of the electrolyte is reduced, since a large proportion of thepores is reduced in size or even closed by laminating the washed films.Therefore, it is particularly preferable to wash the cell afterlamination only. The washing step yet causes tensions and decontactingsin a cell produced with said film; the mechanical stability is thusconsiderably affected. Also, electrochemical decompositions are observedif the cell is activated in a later stage. A further disadvantage is thedirect contact of the subsequently filled-in liquid electrolyte with thecontact gauzes which are usually made from aluminum on the positive sideand from copper on the negative side, said direct contact being due tothe porous structure. Consequently, decompositions of the electrolytebetween two metals without reference can occur.

Neither is it advantageous therefore to incorporate the electrolytehomogeneously into the organic paste material provided for theproduction of the films, as has been proposed so far, nor is itadvantageous to provide a high degree of porosity of the films that hasto be provided by washing out plasticizer—usually several times.

The problem of the present invention is to provide films having improvedproperties from which electrochemical structural elements, particularlyaccumulators and batteries, can be produced in the form of thincomposite layers. The films thus produced shall not present theaforementioned disadvantages of prior art. Moreover, paste-like massesare provided from which such films can be produced.

SUMMARY OF THE INVENTION

In order to solve this problem, it is proposed to neither produce thefilms from a paste having homogeneous components, i.e. electrochemicallyactivatable materials that are soluble in the polymer material, nor toprovide electrochemically active composite films having a high degree ofporosity, the ion conduction of which exclusively occurs by the aid of aliquid. Rather, paste-like masses that can be used in electrochemicalstructural elements for producing respective films are provided thatcomprise a heterogeneous mixture of a matrix (A) containing at least oneorganic polymer, precursors thereof, or prepolymers thereof, and ifdesired a plasticizer, or consisting of said components, and anelectrochemically activatable inorganic material in the form of a solidsubstance (B), said material not being soluble in said matrix. Inaddition, films and electrochemically active composite layers producedfrom said masses are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in the attached drawings, in which:

FIG. 1 demonstrates the cycle behavior (11^(th)-22^(nd) cycle) of a cellin accordance with claim 20;

and FIGS. 2 a and 2 b each show an enlarged view of a detail of cycleno. 12.

DETAILED DESCRIPTION OF THE INVENTION

The term “that can be used in electrochemical elements” implies that theelectrochemically activatable inorganic material that is in the form ofa solid substance must be an ion-conducting or electron-conductingmaterial that is suitable as an electrode material or as a solidelectrolyte.

Since the films are produced from heterogeneous paste mixtures, theparameter which determines the kinetics for the chemical diffusion, i.e.for the transport of atoms into and out of the active material of thenegative and of the positive electrodes, is the grain size being in theμm range and not the thickness of the film which is higher by at leasttwo orders of magnitude. This is because the chemical diffusion ismathematically described by the diffusion coefficient

$\begin{matrix}{{\overset{\sim}{D} = \frac{L^{2}}{2t}},} & (1)\end{matrix}$wherein L is the diffusion length and t is the diffusion time. Whensolving said formula with regard to the time t, one obtains

$\begin{matrix}{t = \frac{L^{2}}{2\overset{\sim}{D}}} & (2)\end{matrix}$

The diffusion time determines rapid electrode kinetics and relaxationand therefore the maximum possible current discharge and service life(high polarizations are detrimental to the host lattice of theelectrodes) of an accumulator or another electrochemical structuralelement. The time can be influenced either by the geometry, i.e. theeffective diffusion length, or by the diffusion coefficient, i.e. by avariety of electrode materials, the diffusion coefficient itself beingan electrochemical material property. Since electrode materials on theone hand should meet capacity, environment and cost requirements, and onthe other are responsible of the desired volumetric and gravimetricperformance density of the electric structural element (e.g. of theaccumulator), it is easier in most cases to reduce the diffusion length.

The proposal of using electrochemically active powders (material (B)),the grain size of which is as small as possible, results therefrom. Itis required that said powders are embedded in a mixed conducting, i.e.both, ion and electron conducting matrix, wherein both the ionconduction and the electron conduction in said matrix have to besufficiently rapid to have no decelerating effect, and thus, thecriterion{tilde over (D)}_(matrix)>>{tilde over (D)}_(electrode material)  (3)has to be fulfilled, since the matrix determines the effective geometryof the cell. Thus, because the chemical diffusion is a mixed and asimultaneous transport of ions and electrons, the rapid transport ofboth species over and through the matrix becomes essential, in case theadvantage of the small diffusion length in the μm range of the electrodematerial shall be made use of.

The most conductive metals have a conductivity σ of 10⁶ S/cm;immediately followed by specific modifications of the carbon. Thehighest ionic conductivities are achieved in molten salts or inconcentrated H₂SO₄, being in a range of 10⁰-10¹ S/cm. The best organiclithium ion conductors are in a range of 10⁻² S/cm; they are used inlithium cells. Therefore, the general statementσ_(bionic)<<σ_(electronic)can be made. Whereas the requirement with regard to the electronicconductivity can be met easily by adding carbon blacks having a highconductivity, an electrolyte has to be present in the film in a formwherein it is finest and best dispersed in order to compensate thedisadvantage in conductivity by the geometry of a large surface.

Therefore, a material (C) is added to the mass provided for the paste inaccordance with the invention, said material preferably beingelectrochemically inert to a large extent, but having a transport and/ora storage and/or a swelling effect for a liquid electrolyte.

The films (negative electrodes, positive electrodes and electrolytes)produced from these pastes can be laminated to obtain a composite filmwhich can subsequently be impregnated with the solution ofa—second—electrolyte, or the electrolyte film is separately filled withsaid solution of a second electrolyte already prior to the production ofthe composite layer. Preferably, said material (C) is not only added tothe pastes that are provided for the production of an electrolyte film,but also to those pastes from which electrode films shall subsequentlybe produced in order to ensure the maintenance and mobility of theelectrolyte also in the electrodes.

The attached figures illustrate the present invention, FIG. 1demonstrating the cycle behavior (11^(th)-22^(nd) cycle) of a cell inaccordance with claim 20, whereas FIGS. 2 a and 2 b each show anenlarged view of a detail of cycle no. 12.

The material (C) may optionally be selected from among all thosesubstances and mixtures thereof that due to their structure and incombination with matrix the (A) due to a capillary effect or the like,respectively, will increase the absorption capacity for an electrolytesolution of the films produced from the paste. For example, materialscan be selected that due to their porous structure, their high specificsurface or their high swelling capacity, develop strong capillary forcesfor the electrolyte solution to be absorbed. It is possible that saidmaterial (C) has ionic or electronic conductivity properties that areimportant for the electrochemistry of the films or of theelectrochemical structural elements, respectively. Preferably, however,said material (C) is electrochemically inert or substantially inert.

Examples of substances that can be used as material (C) are pumicepowder, zeolites, carbon nanotubes, chamotte or silica gel, acetyleneblack, activated carbon, lampblack, carbon blacks, carbons having a highspecific surface and/or conductivity (e.g. Printex carbon blacks byDegussa) fumed silica (e.g. Cab-osil by Fluka), or kieselguhr. In fact,part of said substances have already been proposed to be used assupporting or filling agents. However, this was never the case inconnection with a film or a composite film, respectively, that is/are tobe filled further with an electrolyte.

Said material (C) can favorably be incorporated into the paste-like massin a quantity of 0.05-50% by weight, preferably in a quantity of about 2to 10% by weight, relative to the total components of the pastematerial.

According to a particular embodiment of the invention, theelectrochemically active or activatable material (B) itself also hassuch an absorption and maintaining capacity for the electrolyte.Materials having said property are for example MCMB (mesocarbonmicrobeads, that can be produced by condensation of tar at 400° C. andsubsequent graphitization of the material obtained at a temperature of2800° C.) as a material for a (negative) electrode, or natural spodumenehaving a grain size of ≦75 μm, preferably of ≦40 μm, most preferably of≦1 μm as an electrolyte material. Such materials can be processed in anexcellent manner together with the remaining components of said matrix(A) to obtain a mechanically stable film; also, they easily absorb anelectrolyte solution. In extreme cases, the addition of a material (C)is therefore completely dispensable.

The mass obtains its paste-like consistency by using a suitable matrix(A). The term “paste-like” shall mean that the mass, once it has beenproduced, can be processed using usual paste application methods, forexample by calendering, extrusion, casting, brushing, spatula coating,knife coating, or it can be applied to a base by various printingmethods, whereby mainly but not exclusively self-supporting layers shallbe produced. Depending on the need, the mass can be made to berelatively thin to very viscous.

A plurality of materials can be used for the matrix (A). Systemscontaining solvents or solvent-free systems can be used. Solvent-freesystems that are suitable are, for example, cross-linkable liquid orpaste-like resin systems. Examples are resins made of cross-linkableaddition polymers or condensation resins. For instance, pre-condensatesof phenoplasts (novolaks) or aminoplasts can be used that are finallycross-linked to the layer of an electrochemical composite layer afterthe paste-like mass has been formed. Additional examples are unsaturatedpolyesters, such as polyesters that can be cross-linked to styrene bygraft copolymerization, epoxy resins that are curable by bifunctionalreaction partners (for example bisphenol A epoxy resin, cold cured withpolyamide), polycarbonates that can be cross-linked such as apolyisocyanurate that can be cross-linked by a polyol, or a binarypolymethyl methacrylate, which can also be polymerized with styrene. Inany of these cases, the paste-like mass is formed from the more or lessviscous pre-condensate or non-cross-linked polymer and the plasticizeras matrix (A), or using essential components thereof, together withcomponent (B).

Another option is the use of polymers or polymer precursors togetherwith a solvent or swelling agent for the organic polymer. In principle,there is no limit in terms of the synthetic or natural polymers that canbe used. Not only polymers with a carbon backbone chain can be used, butalso polymers containing hetero ions within the backbone chain, such aspolyamides, polyesters, proteins, or polysaccharides. The polymers canbe homopolymers or copolymers; the copolymers can be statisticalcopolymers, graft copolymers, block copolymers, or polyblends, there isno limitation. In terms of polymers with a pure carbon backbone, naturalor synthetic rubbers can be used, for instance, halogenated, e.g.fluorinated hydrocarbon polymers such as Teflon, polyvinylidene fluoride(PVDF), polyvinylidene chloride, or polyvinyl chloride are particularlypreferred, since these make it possible to obtain particularly goodwater-repellant properties of the films or layers formed from thepaste-like mass. This imparts particularly good long-term stability tothe electrochemical structural elements thus produced. Additionalexamples are polystyrene or polyurethane. Particularly preferredexamples of copolymers are copolymers of Teflon and of amorphousfluoropolymer, as well as polyvinylidene fluoride/hexafluoropropylene(commercially available as Kynarflex). Also, other polymers that arecapable of swelling, such as polyethylene oxide, are preferred. Examplesof polymers having heteroatoms within the main chain are polyamides ofthe diamine dicarboxylic acid type or of the amino acid type,polycarbonates, polyacetals, polyethers, and acrylic resins. Othermaterials include natural and synthetic polysaccharides (homeoglycansand heteroglycans), proteoglycans, for example, starch, cellulose,methylcellulose. In addition, substances such as chondroitin sulfate,hyaluronic acid, chitin, natural or synthetic waxes, and many othersubstances can be used. In addition, the aforesaid resins(precondensates) can be used in solvents and diluents.

The aforementioned substances are incorporated into the paste materialin a suitable manner in a quantity of 0.05 to 50% by weight, preferablyin a quantity of 2 to 30% by weight, relative to the total quantity ofsaid paste material. A quantity of ≦10% by weight is often sufficient.

One skilled in the art is familiar with solvents and swelling agents forthe aforesaid polymers.

A plasticizer (also designated as softener) for the polymer(s) used isan optional component of the matrix (A). “Plasticizer” or “softener”should be understood to define substances the molecules of which arebonded to the plastic molecules by secondary valence forces (Van derWaals forces) and which thus reduce the interacting forces between themacromolecules and therefore reduce the softening temperature and thebrittleness and hardness of the plastics. Thus, a number of substanceswhich are usually designated as swelling agents is understood to becomprised therein. Using a plasticizer in accordance with the inventioneffects high mechanical flexibility of the layer that can be producedfrom the paste-like mass.

In accordance with the invention, the electrochemically activatablematerial of the paste-like mass (B) is not soluble in the plasticizer(nor of course in the solvent or swelling agent possibly used for thepolymer).

It is particularly preferable to select the plasticizer from amongsubstances and mixtures of substances carrying the group

wherein independently of each other A¹ and A² can be R¹, OR¹, SR¹ orNHR¹, or A¹ and A² together with D form a hetero-5-ring, and D can beC═O, S═O, C═NH or C═CH₂ and further, if D forms said hetero-5-ring withA¹ and A², D can also be O, S, NH or CH₂. R¹ is a (straight-chain orbranched-chain optionally cyclic) C₁C₆ alkyl radical. Preferably, R¹ ismethyl, ethyl, n- or iso-propyl, n- or iso-butyl.

By the aforesaid criterions, mainly carbonates or esters and theirsulfur and amino analogues are comprised. Substances that areparticularly preferred as plasticizer are dimethyl sulfoxide, dimethylcarbonate, ethyl methyl carbonate, diethyl carbonate, methyl propylcarbonate, ethylene carbonate, ethylene sulfite, N—N′-ethylene urea,propylene carbonate, dioxolane, tetrahydrofurane, and butyrolactone.

In the composition according to the invention, the plasticizer has adirect effect on the consistency, homogeneity and flexibility of thefilm. Substances having an asymmetric ring structure are particularlypreferred; very good results are also obtained with a symmetric ringstructure, said results being only slightly inferior to those of thefirst group. Without a closed ring, the result goes somewhat down,possibly due to an increased volatility. Particularly surprisingly, thestorage life and the flexibility of the material are considerablyimproved, even if the plasticizer proportion is very small. Theseproperties are so much more astonishing as many substances which arecomprised by the definition of the plasticizer to be used according tothe invention have rather been known as swelling agents so far.

It is preferred to use the plasticizer in a quantity that is not toolarge. 0.05-50% by weight can be suitable; up to 12% by weight arepreferably, about 10% or less are more preferably, and not more thanabout 5% by weight are most preferably present in the matrix, thequantity being in relation to the quantity of the electrochemicallyactivatable material. It is recommended to keep the quantity ofplasticizer always as small as possible for the respective system. If itis desirable for technical processing considerations to incorporate arelatively large quantity into the paste-like mass, part of theplasticizer can subsequently (e.g. after forming the film) be removed,for instance by vacuum extraction e.g. at up to 10⁻² mbar, if necessaryat an increased temperature (up to about 150° C., preferably at 65-80°C.). Alternatively, the extraction can be effected at ambient pressureby drying and heating at preferably 120° C., if necessary up to 200° C.

An advantage of small plasticizer quantities is, among others, thereduction of the incorporation of water into the films (plasticizers areusually hygroscopic), which might remain there and be enclosed therein.In accordance with the invention, an extremely small inclusion of waterduring production is achieved, and the films thus produced can easilyand elegantly be dried using standard methods.

The paste-like mass, if provided for producing an electrode film, mayfurther contain a conductivity improving agent (D), preferably in aproportion by weight of about 2 to 35% by weight, relative to the solidsubstance (B) that is suitable as an electrode material. Carbon black,graphite, elementary metals, nitrides or mixtures of said substances mayfor example be used as conductivity improving agents.

From the inventive paste-like masses, thin layers, e.g. films, areproduced from which thin-film batteries and other similarelectrochemical structural elements can be produced. The individuallayers or films of these elements are also called “tapes”. Said layersor films or those obtained therefrom by suitably placing the respectiveelectrochemically active or activatable layers upon one another cansubsequently be immersed into a suitable electrolyte solution, asmentioned.

The present invention therefore furthermore comprises electrochemicallyactive or activatable layers or films that can be produced from thepaste-like masses described in the foregoing, that are self-supportingor that are placed on a substrate, preferably in the thicknessesindicated. The layers are preferably flexible.

The consistency of the films is a result of use of the matrix (A)described above in more detail, said matrix consisting of supportingpolymers as described above which if necessary (and preferably) aresoluble in a solvent like acetone, and if desired of one or moreplasticizer(s) (softener(s)) as described above. Further, they contain apowdered electrode or electrolyte material (B) that is insoluble in thefilm. If electrode films are concerned, a conductivity improving agent(D) as described above for the paste-like masses can preferably becontained in addition. In accordance with the invention, they furthercontain a material (C) as described above for the paste-like masses,said material being capable of improving the transport and the storageof a liquid electrolyte within the film. Whereas the solvent that isoptionally used for producing the paste is preferably removed during orafter the paste has solidified to film shape (e.g. by degasifying invacuum and/or by heat), the plasticizer, if present, preferably remainsat least partly in the film obtained. The fact that the plasticizerremains in the film contributes to avoiding sedimentation of powderedcomponents during film production. In fact, many of the polymercompositions described in the foregoing (e.g. a preferred composition ofa copolymer of polyvinylidene fluoride/hexafluoropropylene, (PVDF/HFP,Kynarflex) or a composition using substantial parts thereof) have only asmall degree of crystallinity, a high flexibility and only a lowtendency to embrittlement. However, a possible separation andsedimentation during film production can not be avoided with certainty.

For producing both the self-supporting layers (films, tapes) and thelayers that can be placed on a substrate, one can fall back to methodsknown in prior art that can be used for the corresponding polymermaterials of the matrix. Important techniques are the so called tapecasting, the so-called “reverse-roll-on-coating”, casting, spraying,brushing, or rolling. The consolidation of the paste-like masses thenoccurs, depending on the material, for example by curing (of resins orother precondensates), by cross-linking prepolymerisates or linearpolymerisates, by evaporating solvents, or in a similar manner. In orderto obtain self-supporting films, a suitable paste-like mass can forinstance be formed in the appropriate thickness on calenders. Standardtechnology can be used for this. Self-supporting layers can also beformed by applying the paste-like mass to a substrate and removing thelayer produced after it has consolidated. The coating process can beperformed using conventional paste application methods. For instance,application can be performed by brush, rake, spraying, spin coating andthe like. Printing techniques can also be used. The lamination of filmsto a composite is effected at a suitable temperature, for the systemPVDF/HFD mentioned before for instance in an appropriate manner at100°-250° C., preferably in the range of 135-150° C. If necessary,temperature gradients may be applied. Continuous films can be laminatedin a dynamic continuous way using a pressure of preferably about 0.5kg/20 cm².

In one embodiment of the invention, cross-linkable resin masses(pre-condensates) are used as described above for the paste-like masses,and are cured by UV or electron radiation once the layer has beenformed. Curing can naturally also be thermal or chemical (for example byimmersing the produced layer in an appropriate bath). If necessary,suitable initiators or accelerators or the like are added to the massesfor respective cross-linking.

The production of films provided for electrochemical structural elementsin accordance with the invention has a number of advantages: (a) Theproduction of large numbers of pieces having the storage life of thebasic materials is favorable (the layers that have not yet beenconnected to an electrochemical composite layer can be stored verysafely). (b) A flexible and variable shaping is possible. (c) The filmscan be stored in a space-saving manner (e.g. by stacked and/or rolled upfilm webs). (d) Due to the absence of low-boiling materials and to thepresence of solid ion conductors, a higher temperature resistance isobtained. (e) Due to the solid condition of the electrochemicallyactivatable components, the films are leakage-safe andcorrosion-resistant. (f) Since in a preferred manner, matrices andplasticizers are used that are substantially recognized as safe withregard to health, the binding material can be extracted after use, andthe basic materials can be recovered by filtration and can be recycled.As mentioned, the films, after having been produced, are impregnatedwith a (second) dissolved electrolyte prior to being laminated to acomposite layer or thereafter. This can for instance be effected byspraying an electrolyte solution onto the film or onto the laminatedcomposite film or by immersing the film or the composite film into therespective electrolyte solution. This can be effected in a particularlypreferred manner with such films/composite films from which excessplasticizer has been removed in advance as described above, or for whichonly a very small quantity of plasticizer has originally been used.After impregnating the film or the composite film, it is advantageouslydried. Whereas this is usually effected by heating it for some hours,e.g. maintaining it at a temperature of 70-90° C., the addition of thematerial (C) provides for a reduction of this time and/or a conversionalready at room temperature. During this “conversion”, a very thin,flexible, ion conducting layer of reaction products of polymer, softenerand electrolyte can be formed. As a consequence of the absorptionprocess described, the electrolyte is jellified or solidified; despitethe use of a dissolved electrolyte, the tape or the cell (i.e. the filmor the composite film) thus obtained is particularly leakage-safe.

Suitable electrolytes are, for instance, salts of lithium. LiClO₄,LiNO₃, LiBF₄, LiPF₆, LiSO₃CF₃, LiC(SO₂CF₃)₃ or Li(CF₃SO₂)₂N or mixturesthereof are used with particular advantage. Further, explosivesubstances, like the perchlorate or nitrate salts that have beenmentioned above, can be used due to the jellification or solidification,without an explosion possibly occurring when charging even with highcurrents, since an explosion-safe system (cell) is provided by theinventive absorption and bond of the liquid electrolyte. Preferably,plasticizers are used as solvents that have been defined above as anoptional component of the matrix (A), and among them preferably suchplasticizers having the group A¹-D-A², as also defined above, alone orin mixture. The plasticizer selected or the plasticizer mixture selectedshould be liquid at the processing temperature.

According to a preferred embodiment of the invention, the solvent forthe electrolyte comprises a substance having good swelling properties.Said substance can for example be one of the aforementionedplasticizers, when having such properties, e.g. propylene carbonate.Such a substance is particularly preferably contained in a quantity of 2to 10% by weight, more preferably of about 5% by weight, relative to thetotal solvent for the electrolyte. If a too large quantity of such asubstance is added or if plasticizers are used as solvents for theelectrolyte that in all have a too strong swelling effect, said toostrong swelling first causes decontactings within the cell, thenpossibly leading to a complete softening and decomposition of the cell.On the contrary, if swelling is only moderate, said swelling has theeffect that the electronic and ionic contact within the films and of thefilms with each other is improved by closing small cavities, which canoccur for example by extraction of the solvent, when the films aredried.

In a further special embodiment of the invention, the film matrix (A)contains a plasticizer, and the liquid electrolyte provided for theimpregnation contains or consists of an electrolyte that is alsodissolved in the plasticizer. The same, another or partly anotherplasticizer may be present in the matrix (A) or may serve as a solventfor the electrolyte, respectively. The quantity of plasticizer that ispresent in the film is preferably selected such that the film is not,particularly by far not saturated with the plasticizer—said selectionbeing made by the addition of respective quantities during theproduction of the basic paste-like masses, or by extracting a partthereof later, as described in the foregoing. Consequently, during theimpregnation with the electrolyte solution, the plasticizer penetratesinto the film via the existing concentration gradient and serves as avehicle for the absorption of the dissolved electrolyte material. Inextreme cases, the complete electrolyte can be transferred into the filmthis way, so that a material (C) as defined in the foregoing is notrequired in the film at all.

The inventive films are not particularly limited in their thickness(width); one skilled in the art will respectively select the thicknesswhich is appropriate for an application. For instance, suitablethicknesses are from about 10 μm, more preferable from about 50 μm, upto about 1 to 2 mm and if necessary more (e.g. up to about 10 mm, suchfilms possibly being provided for stamping out small-dimensioned forms,e.g. for batteries and accumulators to be used in medicine, such ashearing aid batteries). Films for the production of electrochemicalstructural elements in so-called “thick-layer technology” have athickness in the range of preferably about 50 μm to 500 μm, mostpreferably in the range of about 100-200 μm. In accordance with theinvention it is, however, also possible to produce correspondingthin-layer structural elements (this term comprises thicknesses ofpreferably 100 nm up to a few μm). This application may, however, berestricted, since in a plurality of cases, corresponding structuralelements may not satisfy usual capacity requirements. The applicationfor backup chips is however possible.

The present invention furthermore relates to composite layers havingelectrochemical properties, particularly such as rechargeableaccumulators and other batteries that are formed by or comprise acorresponding sequence of the aforesaid layers.

For producing composite layers, the individual paste-like masses can beapplied layer by layer upon one another by means of paste applicationmethods. Either each individual layer can be cross-linked per se or itcan be freed from solvent or made into layer form in some other manner;however, it is also possible to consolidate the individual matrices bycross-linking or evaporating the solvent or swelling agent or the likeonce application of all of the required layers has been completed. Thislatter is advantageous, for instance, if the individualelectrochemically activatable layers are applied using a printing methodthat occurs analogous to polychromy. An example of this is theflexographic printing technique, by means of which multiplemeters/second of a substrate can be imprinted continuously with therequired electrochemically activatable layers.

Alternatively, every layer or film can be converted individually intoits final consolidated state. If these are self-supporting films, theappropriate components of the structural element to be formed can bestored separately, e.g. as rolled films, and subsequently be joinedtogether by lamination. Conventional laminating techniques can be usedfor this. These include, for example, extrusion coating, whereby thesecond layer is bonded to a carrier layer by pressure rollers, calendarcoating using two or three roll nips, wherein the substrate web runs inin addition to the paste-like mass, or doubling (bonding under pressureand counterpressure of preferably heated rollers). One skilled in theart will not have any problem finding the techniques that areappropriate depending on the selection of the matrices for thepaste-like masses.

As stated in the foregoing, the inventive paste-like masses and layersor films produced therefrom are suitable for a plurality ofelectrochemical structural elements. One skilled in the art is able toselect the same solid substances (B) that he would use for classicelectrochemical structural elements, that is, substances (B) to which noplastics have been added.

In particular for lithium systems that can provide the highest practicalvolumetric and gravimetric energy densities, one is dependent on films.This is due to the requirement that large contact surfaces forcompensating the ionic conductivity have to be provided, which, in turn,is smaller by three orders of magnitude compared to aqueous systems.Markets with high piece numbers in million, like the 3C market, requirea continuous production method via films from the roll, since otherwisethe required cycle times are not achievable.

In the following, a number of such lithium systems shall be mentioned asan example:

lower contact electrode Al, Cu, Pt, Au, C positive electrode allpossible combinations of multinary compounds of lithium cobalt oxides,lithium nickel oxides and lithium manganese oxides, optionallysubstituted with magnesium, aluminum or fluorine electrolyteLi₁,₃Al₀,₃Ti₁,₇(PO₄)₃, LiTaO₃•SrTiO₃, LiTi₂(PO₄)₃•Li₂O, Li₄SiO₄•Li₃PO₄,negative electrode carbon (in an optional modification), TiO₂, TiS₂,WO₂, MoO₂, lithium titanate, a lithium- alloyable metal, oxide, iodide,sulfide or nitride, a lithium-alloyable semiconductor and heterogeneousmixtures thereof upper contact electrode Al, Cu, Mo, W, Ti, V, Cr, Ni

Examples of use are lithium cells, lithium polymer cells, lithiumplastic cells, lithium solid body cells or lithium ion cells.

However, the present invention is of course not limited tolithium-technology accumulators, but rather, as stated in the foregoing,comprises all systems that can be produced using “conventional”technology, that is, without incorporating an organic polymer matrix.

The following describes a few special embodiments of the paste-likemasses that are suitable for special structural elements or structuralelement parts. For those electrochemically activatable parts that arenot prior art, it should be clear that these substances can also be usedin “bulk form”, i.e., without the polymer matrix in appropriateelectrochemical structural elements.

Appropriately selecting the electrochemically active substances makes itpossible to produce electrochemical structural elements, such asaccumulators, whose characteristics in the charge/discharge curves makeit possible to selectively control the charge/discharge status of theaccumulator. Thus, mixtures of two of the electrode materials cited inthe foregoing, or of other appropriate electrode materials, can be usedas electrochemically activatable solid substance (B) for the positive ornegative electrodes, the materials having different oxidation andreduction stages. Alternatively, one of the two substances can bereplaced with carbon. This results in characteristic runs or courses inthe charge/discharge curves which makes it possible to advantageouslydetect the charge or discharge status of an accumulator produced usingsuch masses. The curves have two different plateaus. If the plateau thatis near the discharge status is achieved, this status can be indicatedto the user so that he knows that he will soon need to recharge, andvice versa.

If carbon and an element that can be alloyed with lithium isincorporated into a paste-like mass provided for a negative electrode,this imparts to the electrode (with properties of an alloy electrode andan intercalation electrode) that can be produced therefrom aparticularly high capacity that has improved electrochemical stability.In addition, the expansion in volume is lower than in a pure alloyelectrode.

If the paste-like mass according to the invention is provided for anelectrode, a conductivity improving agent (D) can be added additionally,as already mentioned. Graphite or amorphous carbon (carbon black) or amixture of the two, but also a metallic powder or a nitride aresuitable. Weight proportions of about 2.5 to about 35% by weightamorphous carbon relative to the electrochemically activatable componentare particularly advantageous in this regard. If the mass is providedfor a positive electrode, the lubricating effect of the carbon is anadvantageous property to be mentioned that improves the mechanicalflexibility of a layer produced from the paste-like mass. If the mass isprovided for a negative electrode, additionally the electrochemicalstability and the electronic conductivity are improved, as has beendescribed in the foregoing.

The inventive paste-like mass can also be used for electrodes other thanintercalation electrodes. An example of this is the use of metallicpowder in combination with an alkali or earth alkali salt as theelectrochemically activatable solid substance (B). A paste-like massproduced with this combination can be used to produce decompositionelectrodes. The expansion in volume that is typical for intercalationelectrodes does not occur in this case, which results in improvedservice life over time. An example of this is the combination of copperand lithium sulfate.

Surprisingly it has also been demonstrated that incorporating a phasemixture into the inventive paste-like mass consisting of Li₄SiO₄.Li₃PO₄,regardless of its intended electrochemical application, leads to animprovement in the plasticity of the electrodes or solid electrolytesproduced therefrom. This requires that the phase mixture be groundextremely fine. The extremely small grain sizes must be the reason foran improved internal sliding effect.

Regardless of whether the solid substance (B) is an electrode materialor an electrolyte material, it can consist of a lithium ion conductorand one or more additional ion conductors (Li, Cu, Ag, Mg, F, Cl, H).Electrodes and electrolyte layers made of these substances haveparticularly favorable electrochemical properties such as capacity,energy density, mechanical and electrochemical stability.

The components described in the foregoing from which the inventivepaste-like mass is produced can be mixed in a conventional manner,preferably by vigorously agitating or kneading the components.Preferably, the organic polymer or its precursors are pre-dissolved orpre-swollen with the plasticizer in a solvent or swelling agent beforethe component (B) is added.

Embedding the solid substances (B) in the matrix (A) means that thepowders of the electrochemically activatable substances do not have tobe sintered at high temperatures, as is customary for “conventional”electrochemical structural elements. Such sintering would not result inthe initial substances having a paste-like consistency.

The electrochemical structured parts that can be produced with theinventive paste-like masses are not limited. It is therefore understoodthat the embodiments described in the following are merely examples orparticularly preferred embodiments.

Rechargeable electrochemical cells can be produced in this manner usingthick-layer technology, i.e. with individual electrochemicallyactivatable layers having a thickness of approximately 10 μm toapproximately 1 to 2 mm and preferably of approximately 100-200 μm. Ifthe electrochemical cell is to be based on lithium technology, the solidsubstances for the electrodes or electrolyte layers can be thosesubstances that have already been enumerated in the foregoing for thispurpose. At least three layers have to be provided in such cases,namely, one that functions as a positive electrode, one that functionsas a solid body electrolyte, and one that functions as a negativeelectrode.

In accordance with the invention it has been demonstrated thatparticularly advantageous current densities can be obtained in theaccumulator if certain limits are observed. As is known, current densitycan be adjusted by the resistance of the electrolyte. If it is too high,polarization can destroy the electrodes over the long term; if it is toolow, the power of the produced accumulator is only sufficient for a fewapplications. The aforesaid limit is preferably 1 mA/cm². For instance,if the conductivity of an electrolyte is 10⁻⁴ S/cm, it is particularlyadvantageous for the electrolyte layer to be approximately 100 μm thick.A current density of 1 mA/cm² then causes a drop in voltage, caused bythe resistance, that is a negligible 0.1 V. In contrast, if theconductivity of the electrolyte is 10⁻⁵ S/cm, for instance, thethickness of the electrolyte layer can be reduced to about 10 μm. It istherefore recommended that the layer thickness d be selected relative toconductivity σ_(ion) and to an ionic resistance (Ω) and relative to thesurface A such that the following formula is satisfied:200Ω<d/(σ_(ion) ·A)

The aforesaid three-layer cell (or any other desired electrochemicalstructural element, consisting of positiveelectrode/electrolyte/negative electrode) can additionally be providedwith contact electrodes. It is useful that these comprise films ofsuitable materials (materials for contact electrodes that can be used inlithium technology are described earlier in this specification).

In a special embodiment of the invention, an additional thin plasticlayer (“intermediate tape”) is worked in between the lower contactelectrode and the adjacent electrode and between the upper contactelectrode and the adjacent electrode which plastic layer can also beproduced using a paste-like mass of the present invention. This thinplastic layer should contain conducting metal elements or alloys of suchelements that are suitable for transporting electrons from the electrodematerial to the contact electrode. Examples of this are the elementsgold, platinum, rhodium, and carbon, or alloys of these elements, if theplastic layer is to be arranged between the positive electrode and theassociated contact electrode. If it is to be arranged between thenegative electrode and the contact electrode, the elements that areappropriate are nickel, iron, chromium, titanium, molybdenum, tungsten,vanadium, manganese, niobium, tantalum, cobalt, and carbon. Theinformation provided in the foregoing about the electrodes andelectrolytes also applies, of course, to the concentration and structureof the paste-like masses from which these layers are formed.

The electrochemical structural elements of the present invention can besealed, for example in a plastic-based housing, particularly in analuminum film coated with plastic. The weight in this case isadvantageously less than that of metal housings; there are alsoadvantages in terms of energy density.

The electrochemical composite layer (the electrochemical structuralelement) can also be embedded between two or more films made of aplastic coated with wax or paraffin. These materials act as a seal and,due to their inherent properties, can also exert mechanical pressure onthe composite layer, thereby advantageously achieving improved contactin the composite layer due to the compression.

While the electrochemical element is sealed as described in theforegoing or in some other manner, the interior can be subjected to apre-determined water/oxygen partial pressure that effects highelectrochemical stability. This can be done, for instance, by sealingthe electrochemical element in such an environment using parameters thathave been selected and adjusted appropriately.

The desired sealing can be improved by (again) adding a swelling agent,e.g. propylene carbonate, to the composite film prior to sealing withinor with the respective intended material. Thereby, a tight contact ofall components with each other is provided, the cell is sealed against apenetration of gas, and the migration of liquids within the cell isprevented.

In another embodiment of the present invention, a layer is selected forthe electrolyte layer that consists of two films of differingcomposition that have been laminated to one another, each of which beingadapted to the electrode with which it is in contact. This has apositive effect on the stability of the phase limits between positiveelectrode and electrolyte 1 and between negative electrode andelectrolyte 2. A concrete example of this embodiment is the use oflithium iodide for the electrolyte material of the first layer andLi_(1,3)Al_(0,3)Ti_(1,7)(PO₄)₃ for the electrolyte material of thesecond layer.

The inventive sequences of layers for the electrochemical structuralelements can be arranged in any desired shape. For instance, theflexible composite layers can be rolled up, which achieves aparticularly advantageous geometry for compact accumulators. If theaccumulator has a small volume, this provides a very large activebattery surface.

Non-self-supporting composite layers can also be applied to solid baseslike walls for integrated energy storage (self-supporting compositefilms can of course also be applied or affixed thereto). In this case itis possible to take advantage of large surface areas. The accumulatorsthemselves are not associated with a space requirement. A specialexample of an embodiment of this type is the integration of compositelayers for accumulators into substrates for solar cells. Independentenergy supply units can be created in this manner. Layer sequences foraccumulators can also be applied to solid or flexible substrates inorder to be used as integrated energy storage in electronic structures.

The concrete examples in the following provide a more detailedexplanation of the invention.

EXAMPLE 1

-   1.1. A battery film (negative electrode) for a rechargeable lithium    cell is produced by agitating 6 g highly crystalline graphite    (Timcal SLM 44), 1.5 g acetylene carbon black (battery quality), 0.6    g ethylene carbonate with 1.5 g polyvinylidene fluoride    hexafluoropropylene in about 50 g acetone for at least 4 hours using    either a magnetic agitator or a dissolver. First, the mixture is    heated to 100° C., and having reached this temperature, it is cooled    down to 50° C. and then maintained at said temperature. Once the    agitating time has terminated, the mixture is thickened until it can    be casted or knife-coated, and the film is extruded using a tape    casting equipment. The knife coating slot is selected such that    after drying, a film thickness of 150-200 μm is obtained. The film    is-dried overnight at 70° C. and 1 mbar final pressure in a vacuum    drying cabinet.-   1.2. Example 1.1 is repeated, with the modification that 7.5 g MCMB    (Osaka gas) is used instead of 6 g graphite and 1.5 g acetylene    carbon black.

EXAMPLE 2

-   2.1. A battery film (electrolyte) for a rechargeable lithium cell is    obtained from 9 g finely powdered LiAlSi₂O₆ (spodumene), 0.9 g    ethylene carbonate, 0.9 g pumice powder, 3.0 g polyvinylidene    fluoride hexafluoropropylene, prepared in about 30 g acetone as was    the negative electrode, and extruded to a thickness of 70-100 μm.-   2.2. Further battery films for a rechargeable lithium cell are    prepared from 9.9 g natural spodumene having a grain size in the    range of 75 μm, 40 μm or 1 μm, respectively, 0.9 g ethylene    carbonate, 3.0 g polyvinylidene hexafluoropropylene, treated in    about 30 g acetone like the negative electrode and extruded to a    thickness of 70-100 μm.

EXAMPLE 3

A battery film (positive electrode) for a rechargeable lithium cell isprepared from 8 g finely powdered LiCoO₂(SC 15, Merck), 1.2 g acetylenecarbon black (battery quality), 0.8 g ethylene carbonate, 0.3 g fumedSiO₂ (Cab-osil, Fluka), 2.0 g polyvinylidene fluoridehexafluoropropylene, and about 30 g acetone as was the negativeelectrode.

EXAMPLE 4

The individual films according to examples 1 to 3 are cut to size andthen laminated to a complete individual cell.

The completed cell is partly sealed in an aluminum film that isasymmetrically coated with plastic and has a thickness of 60 μm, thegauzes being in contact with the outside using two contact studs.Subsequently, the cell is activated with a second solid electrolyte thatis added in an absorbable solution and then tightly sealed.

The following table indicates the electrolyte solutions used:

Solvent (% by weight) Electrode EC DMC PC 0.66 mol/l LiBF₄ 64.7 33.3 — 1mol/l LiBF₄ 66.7 33.3 — 1 mol/l LiBF₄ 63.3 31.7 5.0 0.66 mol/l LiClO₄66.7 33.3 — 0.66 mol/l LiNO₃ 66.7 33.3 — EC = ethylene carbonate DMC =dimethyl carbonate PC = propylene carbonate

FIG. 1 shows the cycle behavior of a cell which has been extruded fromfilms according to examples 1.1, 2.1 and 3. The cycles no. 11-22 areillustrated. The 87 mAh cell was constantly charged with a current ofabout C/4 (20 mA), then was constantly charged with a voltage of 4.1 Vuntil the current had decreased to 10%, and subsequently discharged to 3V with about C/4 (20 mA). A high cycle stability and reproducibilitycould be achieved. The different sectional enlargements of cycle no. 12that are shown in FIGS. 2 a and 2 b show an extremely small suddenvoltage difference (IR drop) when being switched from charging todischarging and vice versa. This and the discharge curve remaininghigher than 3.5 V for a long time are directly correlated with aconsiderable decrease of the internal resistance of the cell.

EXAMPLE 5

A battery film for a primary cell is produced by admixing 9 g fine MnO₂(manganese dioxide), 1.2 g acetylene carbon black (battery quality), 0.9g ethylene carbonate, 0.9 g kieselguhr, 3.0 g polyvinylidene fluoridehexafluoropropylene in about 30 g acetone and subsequently treating saidsubstances in accordance with example 1.

Observations generally show that the electrochemical functional andprocessing capability of the films are not affected by the inventiveadditives.

1. Self-supporting layer or layer that is placed on a substrate,comprising a heterogeneous mixture of (1) a matrix (A) containing atleast one organic polymer, precursor thereof or prepolymer thereof, and(2) an electrochemically activatable inorganic material in the form of asolid substance (B), said material being suitable as a solid bodyelectrolyte and not being soluble in said matrix and in water, the solidbody electrolyte selected from lithium salts including titanium ions orphosphate groups, characterized in that said layer additionally containsan electrolyte introduced into said layer in a dissolved form. 2.Self-supporting layer or layer that is placed on a substrate inaccordance with claim 1, characterized in that said matrix (A)additionally contains a plasticizer.
 3. Self-supporting layer or layerthat is placed on a substrate in accordance with claim 2, wherein saidplasticizer is selected from the group consisting of dimethyl sulfoxide,dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methylpropyl carbonate, ethylene carbonate, ethylene sulfite, propylenecarbonate, dioxolane, tetrahydrofurane, γ-butyrolactone and mixturesthereof.
 4. Self-supporting layer or layer that is placed on a substratein accordance with claim 1, characterized in that said plasticizer ispresent in a quantity of 0.05-50% by weight, relative to saidelectrochemically activatable material.
 5. Self-supporting layer orlayer that is placed on a substrate in accordance with claim 1,characterized in that the organic polymer of said matrix (A) is selectedfrom the group consisting of natural polymers, synthetic polymers andmixtures thereof.
 6. Self-supporting layer or layer that is placed on asubstrate in accordance with claim 1, characterized in that said organicpolymer is a polymer which is capable of swelling and is a chlorinatedor a fluorinated polymer selected from the group consisting ofpolyvinylidene chloride, polyethylene oxide, polyvinylidene fluoridehexafluoropropylene copolymer, and mixtures thereof.
 7. Self-supportinglayer or layer that is placed on a substrate in accordance with claim 1,characterized in that said organic polymer is present in a quantity of0.05 to 50% by weight, relative to the total components of the layer. 8.Self-supporting layer or layer that is placed on a substrate inaccordance with claim 1, characterized in that said layer is a flexiblefilm.
 9. Self-supporting layer or layer that is placed on a substrate inaccordance with claim 1, characterized in that said electrolyte has beenintroduced into the layer due to a concentration gradient ofplasticizer, being dissolved in a plasticizer.
 10. Self-supporting layeror layer that is placed on a substrate in accordance with claim 1,characterized in that a liquid electrolyte transported into and storedwithin the layer contains at least one salt of lithium. 11.Self-supporting layer or layer that is placed on a substrate inaccordance with claim 10, characterized in that the at least one salt oflithium is selected from LiClO₄, LiNO₃, LiBF₄, LiPF₆, LiSO₃CF₃,LiC(SO₂CF₃)₃, Li(CF₃SO₂)₂N, or mixtures thereof.
 12. Self-supportinglayer or layer that is placed on a substrate in accordance with claim 1,characterized in that a solvent of a liquid electrolyte transported intoand stored within the layer is selected from solvents which areplasticizers for the matrix (A).
 13. Self-supporting layer or layer thatis placed on a substrate according to claim 1, wherein the solid bodyelectrolyte is selected from the group consisting of natural salts andminerals of lithium, and synthetic lithium salts including titanium ionsor phosphate groups.
 14. Self-supporting layer or layer that is placedon a substrate according to claim 1, wherein the heterogeneous mixtureadditionally comprises: (3) a material (C) which differs from material(B) and which is capable of improving the transport of a liquidelectrolyte into and the storage thereof within the layer.
 15. Compositelayer having electrochemical properties, comprising a layer inaccordance with claim
 1. 16. Composite layer according to claim 15,further comprising a layer suitable as a negative electrode and a layersuitable as a positive electrode.
 17. Composite layer in accordance withclaim 16, characterized in that the self-supporting layer or layer thatis placed on a substrate, after having been laminated, is brought intocontact with an additional swelling agent, and is subsequently sealed ina suitable material or housing.
 18. Composite layer in accordance withclaim 17, wherein the additional swelling agent is propylene carbonate.19. Rechargeable electrochemical cell made in thick layer technology,comprising a composite layer in accordance with claim
 16. 20.Rechargeable electrochemical cell in accordance with claim 19,characterized in that an electrochemically activatable material for thepositive electrode layer is selected from the group consisting oflithium cobalt oxide, lithium nickel oxide, nickel manganese oxide,alone, in mixture, or as a multinary compound, optionally substituted bymagnesium, aluminum or fluorine, and wherein said electrochemicallyactivatable material for the self-supporting layer or layer that isplaced on a substrate is selected from among natural salts and mineralsof lithium, and from synthetic lithium salts, and wherein anelectrochemically activatable material for the negative electrode layeris selected from the group consisting of carbon modification, titaniumdioxide, titanium disulfide, tungsten dioxide, molybdenum dioxide,lithium titanate, a lithium-alloyable metal, semiconductor materials,oxides, iodides, sulfides, nitrides and heterogeneous mixtures thereof.21. Method for producing a composite layer in accordance with claim 15,characterized in that (a) a pasty mass comprising a heterogeneousmixture of (1) a matrix (A) containing at least one organic polymer,precursor thereof or prepolymer thereof, and (2) an electrochemicallyactivatable inorganic material in the form of a solid substance (B),said material being suitable as a solid body electrolyte and not beingsoluble in said matrix and in water, the solid body electrolyte selectedfrom lithium salts including titanium ions or phosphate groups, isadapted to have layer form and the layer thus obtained is optionallydried, (b) said layer is subsequently laminated to other suitable layersto form a composite layer, and (c) the composite layer thus obtained isimpregnated with a suitable, dissolved electrolyte such that saidelectrolyte penetrates into said composite layer, whereupon thecomposite layer is dried at a temperature in the range of roomtemperature up to about 70-90° C.
 22. Method according to claim 21,characterized in that the electrolyte of step (c) is dissolved in aplasticizer, and that the composite layer obtained according to step (b)does not contain any plasticizer or only contains such a small quantityof plasticizer that due to the plasticizer concentration gradient, theelectrolyte solution will penetrate at least partly into the compositelayer.
 23. Method for producing a self-supporting layer in accordancewith claim 1, characterized in that (a) a pasty mass comprising aheterogeneous mixture of (1) a matrix (A) containing at least oneorganic polymer, precursor thereof or prepolymer thereof, and (2) anelectrochemically activatable inorganic material in the form of a solidsubstance (B), said material being suitable as a solid body electrolyteand not being soluble in said matrix and in water, the solid bodyelectrolyte selected from lithium salts including titanium ions orphosphate groups, is adapted to have layer form and the layer thusobtained is optionally dried, and (b) said layer is impregnated with asuitable, dissolved electrolyte such that said electrolyte penetratesinto said layer, whereupon the film is dried at a temperature in therange of room temperature up to about 70-90° C.
 24. Method according toclaim 23, characterized in that the dissolved electrolyte is dissolvedin a plasticizer, and that the self-supporting layer obtained accordingto step (a) does not contain any plasticizer or only such a smallquantity of plasticizer that due to the plasticizer concentrationgradient, the electrolyte solution will penetrate at least partly intothe layer.